What is the tech troubleshooting trick that saved you the most time or money

[FairDos]

Every regular forum user tends to have at least one troubleshooting trick they picked up somewhere along the way that ended up saving them either a genuinely expensive repair, a callout fee, or hours of frustration once they finally figured it out, whether that is a simple restart that fixes a surprising number of issues, a specific setting buried deep in a menu that solved a persistent problem, or a slightly less obvious fix for a common hardware quirk that most people never think to try.

What is interesting about these tricks is how often they get discovered purely by accident or passed along informally from a friend, rather than from any official support documentation, and how often the eventual fix turns out to be embarrassingly simple compared to how long the actual problem was allowed to persist beforehand. So what is the troubleshooting trick that has genuinely saved you the most time, money or frustration over the years?

[MemoryWizard]

Resetting the router by actually unplugging it for a full thirty seconds rather than just switching it off has fixed more connection issues for me than any support call ever has.

[Trinity49]

Learning to check event logs on Windows before calling any tech support line has genuinely saved me hours of being talked through basic steps I had already tried.

[GrimUpNorth85]

Booting into safe mode to isolate whether a problem is software or hardware related has saved me multiple expensive trips to a repair shop.

[RVD17]

Clearing the cache on a slow phone before assuming it needs replacing has extended the usable life of my devices by years at this point.

[Scarlett]

Reseating RAM sticks properly fixed a random crashing issue that I had almost paid a shop to diagnose for me. Took two minutes once I actually knew to try it.

[Saka19]

Checking the actual cable before assuming a device is broken has saved me from at least two unnecessary replacement purchases over the years.